1. Field of the Invention
This invention relates broadly to spring loaded biopsy instruments, and more particularly to flexible needle assemblies for guided biopsy over straight or askew pathways.
2. State of the Art
Prostate health is a significant concern for men over the age of fifty. If prostate cancer is suspected after a physical examination of a patient or after a Prostate Specific Antigens test, then a biopsy is typically performed to collect tissue samples from the prostate for evaluation by a pathologist. Prostate tumors are small growths which can be scattered about different portions of the prostate. Thus, multiple tissue samples (e.g., typically between 9 and 18) are usually taken from the prostate during the biopsy procedure. The physician performing the biopsy is typically guided by an ultrasound device which is inserted into the rectum of the patient, a procedure known as a Transrectal Ultrasound (TRUS) Guided Prostate Biopsy. The ultrasound device includes a probe which generates images of two-dimensional slices of the prostate. In some systems, the two-dimensional images can be processed to construct a three-dimensional model of the prostate.
During a prostate biopsy procedure, a biopsy needle assembly (which includes a biopsy needle and an outer cylindrically shaped cannula which receives and supports the biopsy needle) is utilized for procuring a tissue sample. The needle assembly and cannula are typically coupled to and/or operably disposed within a spring loaded instrument (typically referred to as a biopsy gun). An ultrasonic probe is inserted into the rectum of the patient adjacent the prostate. The ultrasound probe is used to view the prostate and to provide feedback to adjust the positioning and/or depth of the probe and guide assembly in the rectum. The guide assembly is used to guide the distal end of the needle assembly through the rectal wall to a fixed position and orientation adjacent the prostate. The biopsy gun is used to advance the needle of the needle assembly into the prostate. During firing of the biopsy gun, the needle rapidly advances relative to the cannula into the prostate over a distance called the stroke length, which is typically between 15 mm to 25 mm. The needle may define a notch portion which, upon entry into the prostate, functions as a sampling area by causing tissue within the prostate to slip or prolapse into the notch. A second firing of the biopsy gun causes the cannula to advance over the exposed notch portion of the needle in the prostate. As the cannula advances over the exposed notch portion of the needle, it cuts and severs tissue surrounding the needle and traps the tissue within the notch portion, thereby capturing a tissue sample. The needle and cannula are then withdrawn from the patient with the tissue sample captured within the cannula. This process can be repeated at multiple tissue locations in the prostate.
The angle at which an ultrasonic probe and needle guide can be entered into and positioned within the rectum of a patient is limited. Standard biopsy needles known in the art are straight and do not bend during use. Flexible biopsy needles are disclosed in U.S. patent application Ser. No. 11/895,228, an example of which is shown in FIG. 9 herein. A portion of the needle of FIG. 9 is capable of being bent through an angle within guide channels of a needle guide assembly which physically deforms the needle and cannula as they pass therethrough.
The biopsy needle assemblies and firing guns can be at least partially hand operable, such as that disclosed in U.S. Pat. No. 5,368,045, which discloses a one handed biopsy needle instrument employing spring driven releasably latched stylets and cannulas capable of taking multiple specimens while the other hand of the physician is free to manipulate an ultrasound probe. U.S. Pat. No. 6,165,136 to Nishtala discloses a biopsy needle coupled to a trigger mechanism for taking a tissue sample.